1056 extract_levels in paired lung ct (#1058)

Signed-off-by: Wenqi Li <[email protected]>

workaround as mentioned in #1056


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Signed-off-by: Wenqi Li <[email protected]>

Author: wyli

3d_registration/paired_lung_ct.ipynb

@@ -539,7 +539,7 @@
     "    in_channels=2,\n",
     "    out_channels=3,\n",
     "    num_channel_initial=32,\n",
-    "    extract_levels=[0, 1, 2, 3],\n",
+    "    extract_levels=[3],\n",
     "    out_activation=None,\n",
     "    out_kernel_initializer=\"zeros\").to(device)\n",
     "warp_layer = Warp().to(device)\n",